Buzás Péter, Kovács Krisztina, Ferecskó Alex S, Budd Julian M L, Eysel Ulf T, Kisvárday Zoltán F
Department of Neurophysiology, Ruhr-Universität Bochum, Bochum 44780, Germany.
J Comp Neurol. 2006 Dec 20;499(6):861-81. doi: 10.1002/cne.21134.
Excitatory lateral connections within the primary visual cortex are thought to link neurons with similar receptive field properties. Here we studied whether this rule can predict the distribution of excitatory connections in relation to cortical location and orientation preference in the cat visual cortex. To this end, we obtained orientation maps of areas 17 or 18 using optical imaging and injected anatomical tracers into these regions. The distribution of labeled axonal boutons originating from large populations of excitatory neurons was then analyzed and compared with that of individual pyramidal or spiny stellate cells. We demonstrate that the connection patterns of populations of nearby neurons can be reasonably predicted by Gaussian and von Mises distributions as a function of cortical location and orientation, respectively. The connections were best described by superposition of two components: a spatially extended, orientation-specific and a local, orientation-invariant component. We then fitted the same model to the connections of single cells. The composite pattern of nine excitatory neurons (obtained from seven different animals) was consistent with the assumptions of the model. However, model fits to single cell axonal connections were often poorer and their estimated spatial and orientation tuning functions were highly variable. We conclude that the intrinsic excitatory network is biased to similar cortical locations and orientations but it is composed of neurons showing significant deviations from the population connectivity rule.
初级视觉皮层内的兴奋性侧向连接被认为是将具有相似感受野特性的神经元联系起来。在这里，我们研究了这一规则是否能够预测猫视觉皮层中兴奋性连接相对于皮层位置和方向偏好的分布情况。为此，我们使用光学成像技术获得了17区或18区的方向图，并将解剖示踪剂注入这些区域。然后分析了源自大量兴奋性神经元的标记轴突终扣的分布，并将其与单个锥体神经元或棘状星状细胞的分布进行比较。我们证明，附近神经元群体的连接模式可以分别通过高斯分布和冯·米塞斯分布作为皮层位置和方向的函数进行合理预测。这些连接最好用两个成分的叠加来描述：一个空间扩展的、方向特异性的成分和一个局部的、方向不变的成分。然后我们将相同的模型应用于单个细胞的连接。九个兴奋性神经元（来自七只不同动物）的复合模式与模型的假设一致。然而，对单个细胞轴突连接的模型拟合通常较差，并且它们估计的空间和方向调谐函数高度可变。我们得出结论，内在兴奋性网络偏向于相似的皮层位置和方向，但它由与群体连接规则存在显著偏差的神经元组成。
